Genetic differentiation amoung chewing louse populations (Mallophaga: Trichodectidae) in a pocket gopher contact zone (Rodentia: Geomyidae)

Genetic variation amoung populations of chewing lice (Geomydoecus actuosi) was examined in relation to chromosomal and electrophoretic variation amoung populations of their host (Thomomys bottae) at a contact zone. Louse demes were characterised by low levels of genetic heterozygosity (H = 0.039) that may result from founder effects during primary infestations of hosts, compounded by seasonal reductions in louse population size. Louse populations sampled from different hosts showed high levels of genetic structure both within and amoung host localities. Microgeographic differentiation of louse populations is high (mean Fst = 0.092) suggesting that properties of this host-parasite system promote differentiation of louse populations living on different individual hosts. Amoung population differentiation in lice (Fst = 0.240) was similar to host populations (Fst = 0.236), suggesting a close association between gene flow in pocket gophers and gene flow in their lice.